// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
#ifndef MEDIA_FILTERS_JPEG_PARSER_H_
#define MEDIA_FILTERS_JPEG_PARSER_H_

#include <stddef.h>
#include <stdint.h>
#include "media/base/media_export.h"

namespace media {

// It's not a full featured JPEG parser implememtation. It only parses JPEG
// baseline sequential process. For explanations of each struct and its
// members, see JPEG specification at
// http://www.w3.org/Graphics/JPEG/itu-t81.pdf.

enum JpegMarker {
    JPEG_SOF0 = 0xC0, // start of frame (baseline)
    JPEG_SOF1 = 0xC1, // start of frame (extended sequential)
    JPEG_SOF2 = 0xC2, // start of frame (progressive)
    JPEG_SOF3 = 0xC3, // start of frame (lossless))
    JPEG_DHT = 0xC4, // define huffman table
    JPEG_SOF5 = 0xC5, // start of frame (differential, sequential)
    JPEG_SOF6 = 0xC6, // start of frame (differential, progressive)
    JPEG_SOF7 = 0xC7, // start of frame (differential, lossless)
    JPEG_SOF9 = 0xC9, // start of frame (arithmetic coding, extended)
    JPEG_SOF10 = 0xCA, // start of frame (arithmetic coding, progressive)
    JPEG_SOF11 = 0xCB, // start of frame (arithmetic coding, lossless)
    JPEG_SOF13 = 0xCD, // start of frame (differential, arithmetic, sequential)
    JPEG_SOF14 = 0xCE, // start of frame (differential, arithmetic, progressive)
    JPEG_SOF15 = 0xCF, // start of frame (differential, arithmetic, lossless)
    JPEG_RST0 = 0xD0, // restart
    JPEG_RST1 = 0xD1, // restart
    JPEG_RST2 = 0xD2, // restart
    JPEG_RST3 = 0xD3, // restart
    JPEG_RST4 = 0xD4, // restart
    JPEG_RST5 = 0xD5, // restart
    JPEG_RST6 = 0xD6, // restart
    JPEG_RST7 = 0xD7, // restart
    JPEG_SOI = 0xD8, // start of image
    JPEG_EOI = 0xD9, // end of image
    JPEG_SOS = 0xDA, // start of scan
    JPEG_DQT = 0xDB, // define quantization table
    JPEG_DRI = 0xDD, // define restart internal
    JPEG_MARKER_PREFIX = 0xFF, // jpeg marker prefix
};

const size_t kJpegMaxHuffmanTableNumBaseline = 2;
const size_t kJpegMaxComponents = 4;
const size_t kJpegMaxQuantizationTableNum = 4;

// Parsing result of JPEG DHT marker.
struct JpegHuffmanTable {
    bool valid;
    uint8_t code_length[16];
    uint8_t code_value[256];
};

// Parsing result of JPEG DQT marker.
struct JpegQuantizationTable {
    bool valid;
    uint8_t value[64]; // baseline only supports 8 bits quantization table
};

// Parsing result of a JPEG component.
struct JpegComponent {
    uint8_t id;
    uint8_t horizontal_sampling_factor;
    uint8_t vertical_sampling_factor;
    uint8_t quantization_table_selector;
};

// Parsing result of a JPEG SOF marker.
struct JpegFrameHeader {
    uint16_t visible_width;
    uint16_t visible_height;
    uint16_t coded_width;
    uint16_t coded_height;
    uint8_t num_components;
    JpegComponent components[kJpegMaxComponents];
};

// Parsing result of JPEG SOS marker.
struct JpegScanHeader {
    uint8_t num_components;
    struct Component {
        uint8_t component_selector;
        uint8_t dc_selector;
        uint8_t ac_selector;
    } components[kJpegMaxComponents];
};

struct JpegParseResult {
    JpegFrameHeader frame_header;
    JpegHuffmanTable dc_table[kJpegMaxHuffmanTableNumBaseline];
    JpegHuffmanTable ac_table[kJpegMaxHuffmanTableNumBaseline];
    JpegQuantizationTable q_table[kJpegMaxQuantizationTableNum];
    uint16_t restart_interval;
    JpegScanHeader scan;
    const char* data;
    // The size of compressed data of the first image.
    size_t data_size;
    // The size of the first entire image including header.
    size_t image_size;
};

// Parses JPEG picture in |buffer| with |length|.  Returns true iff header is
// valid and JPEG baseline sequential process is present. If parsed
// successfully, |result| is the parsed result.
MEDIA_EXPORT bool ParseJpegPicture(const uint8_t* buffer,
    size_t length,
    JpegParseResult* result);

// Parses the first image of JPEG stream in |buffer| with |length|.  Returns
// true iff header is valid and JPEG baseline sequential process is present.
// If parsed successfully, |result| is the parsed result.
MEDIA_EXPORT bool ParseJpegStream(const uint8_t* buffer,
    size_t length,
    JpegParseResult* result);

} // namespace media

#endif // MEDIA_FILTERS_JPEG_PARSER_H_
